How can I find the program code for javac.exe?
I am calling javac from C # code. I originally found its location just like this:
protected static string JavaHome
{
get
{
return Environment.GetEnvironmentVariable("JAVA_HOME");
}
}
However, I just installed the JDK on a new computer and found that it did not automatically set the JAVA_HOME environment variable. Requiring an environment variable is not acceptable in any Windows application over the past decade, so I need to find javac if JAVA_HOME environment variable is not set:
protected static string JavaHome
{
get
{
string home = Environment.GetEnvironmentVariable("JAVA_HOME");
if (string.IsNullOrEmpty(home) || !Directory.Exists(home))
{
// TODO: find the JDK home directory some other way.
}
return home;
}
}
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If you're on Windows, use the registry:
HKEY_LOCAL_MACHINE \ SOFTWARE \ JavaSoft \ Java Development Kit
If you don't, you are pretty much stuck with env variables. You can find this blog post.
Edited 280Z28:
This registry key refers to the CurrentVersion value. This value is used to find Java home at the following location:HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Development Kit\{CurrentVersion}\JavaHome
private static string javaHome;
protected static string JavaHome
{
get
{
string home = javaHome;
if (home == null)
{
home = Environment.GetEnvironmentVariable("JAVA_HOME");
if (string.IsNullOrEmpty(home) || !Directory.Exists(home))
{
home = CheckForJavaHome(Registry.CurrentUser);
if (home == null)
home = CheckForJavaHome(Registry.LocalMachine);
}
if (home != null && !Directory.Exists(home))
home = null;
javaHome = home;
}
return home;
}
}
protected static string CheckForJavaHome(RegistryKey key)
{
using (RegistryKey subkey = key.OpenSubKey(@"SOFTWARE\JavaSoft\Java Development Kit"))
{
if (subkey == null)
return null;
object value = subkey.GetValue("CurrentVersion", null, RegistryValueOptions.None);
if (value != null)
{
using (RegistryKey currentHomeKey = subkey.OpenSubKey(value.ToString()))
{
if (currentHomeKey == null)
return null;
value = currentHomeKey.GetValue("JavaHome", null, RegistryValueOptions.None);
if (value != null)
return value.ToString();
}
}
}
return null;
}
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For 64-bit OS (Windows 7), the registry key may be located under
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\JavaSoft\Java Development Kit
if you are using 32bit JDK. So, if you've all written code based on the above, repeat the test.
I don't have the whole Microsoft registry redirector / reflection around yet .
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